1. Field of the Invention
The present invention relates generally to ultraviolet sterilizers having watertight functions and, more particularly, to an ultraviolet sterilizer including: a housing which has an inlet through which ballast water is drawn into the housing, and an outlet through which the ballast water is discharged from the housing after the ballast water has been sterilized; and an ultraviolet sterilization unit which is provided in the housing and includes an ultraviolet lamp applying ultraviolet rays to the ballast water to sterilize the ballast water, wherein the ultraviolet sterilizer further includes a cap which supports each of the opposite ends of the ultraviolet sterilization unit, the cap in watertight contact with the housing, so that if the ultraviolet sterilization unit is damaged, ballast water is prevented from being drawn into a reception space which contains external devices disposed outside the cap, and explosive gas which may cause the ultraviolet sterilizer to explode is also prevented from entering the cap.
2. Description of the Related Art
Generally, when cargo ships sail with no cargo, ballast water is loaded in tanks of the cargo ships to keep the ships in balance. However, unfortunately, ballast water used in the cargo ships may damage native marine ecosystems because of the foreign marine creatures which have been contained in the ballast water. Therefore, it is required to treat the ballast water. To date, methods of applying ultraviolet rays to ballast water have been widely used.
FIG. 1 is a block diagram of a conventional ballast water treatment system. FIG. 2 is a sectional view showing an ultraviolet sterilizer of the conventional ballast water treatment system. In the conventional ballast water treatment system, a supply pump 11 supplies ballast water to an ultraviolet sterilizer 12, and the ultraviolet sterilizer 12 sterilizes the ballast water and discharges it into a tank 13. A control unit 14 controls the entirety of the system.
In the conventional ultraviolet sterilizer 12, a through hole is formed through a housing cover 121 to facilitate replacement of a sleeve pipe 123 and an ultraviolet lamp 1241. A cap 122 having a cylindrical shape which is open on upper and lower ends thereof is removably coupled to the through hole of the housing cover 121. The cap 122 supports the sleeve pipe 123. The ultraviolet lamp 1241 is disposed in the sleeve pipe 123 and supported by a support 125. Furthermore, a cap cover 126 is removably coupled to an upper end of the cap 122 by screws or the like. A passing hole 1261 is formed through the cap cover 126 so that a lead wire 124 of the ultraviolet lamp 1241 is led out of the cap 122 through the passing hole 1261.
However, the sleeve pipe 123 or the ultraviolet lamp 1241 may be damaged on accident or by impurities drawn into the ultraviolet sterilizer during the process of sterilizing ballast water. In this case, ballast water which has been in the ultraviolet sterilizer may leak out of the cap through the junction between the cap 122 and the cap cover 126 or the passing hole 1261 of the cap cover 126 and enter a reception space S which contains several devices for operating the ultraviolet sterilizer. Such leaking may damage the devices of the ultraviolet sterilizer.
Moreover, several devices or machines are present around the ultraviolet sterilizer. Particularly, explosive gas may be present around the ultraviolet sterilizer. If explosive gas enters the cap 122, the ultraviolet sterilizer may be exploded by a spark.